Moriarty makes his bow against the Bulls at Loftus Versfeld in the opening round of the BKT United Rugby Championship.
The wheel has come full circle for the 54-times capped Wales back row man, who despite being born in St Helens when his father, Paul, was playing rugby league, grew up in Swansea.
A brief flirtation with England at U18 and U20 level gave everyone an insight into his talent before he switched his allegiance to Wales.
He was a British & Irish Lion in New Zealand in 2017, a Grand Slammer with Wales in 2019 and also played in the march to the semi-finals at the 2019 World Cup in Japan.
Now he has returned to Wales after two seasons in French rugby at Brive and finds himself facing his old coach Johan Ackermann in Pretoria.
Ackermann has taken over from Jake White as the head coach at the Bulls, who were runners-up in the URC last season, and coached Moriarty for a year at Gloucester.
This season it is Ospreys head coach Mark Jones who will feel the benefit of having the 31-year-old in his squad.
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“We want Ross to be a leader but ultimately we want him to just do what he is good at. We want him to lead with ball in hand, with his collision game and show us what he is about,” said Jones, who has picked him in his starting XV to face the Bulls.
“He makes an impact in defence and he is also a very good lineout forward. He is very keen to get out there, which is fantastic, and he has such energy. The more he plays the more settled he will get."
He will have to wait a week before getting the chance to line up alongside Ospreys skipper Jac Morgan, but with Morgan Morse, Harry Deaves and Morgan Morris to pick from in the back row there is plenty of talent available to Jones.
New Wales caps from the summer tour to Japan, Reuben Morgan-Williams and Keelan Giles, both start and Dan Edwards I now an automatic choice at No 10. James Ratti, who also toured in Japan, will make his 50th appearance for the ospreys when he comes off the bench.
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“We haven’t opened our season out here since the South Africans have been involved in the competition, so it’s very different," said Jones.
“It’s a great opportunity to get away as a group at the end of your pre-season. The South African teams are always strong whether their international contingent is there or not.”
Ackerman may be missing a number of Springboks, but he still has seven to call on and will have four of the pack and three of the back line who started in the URC Final defeat to Leinster in Dublin at the end of last season.
Bulls: Devon Williams; Cheswill Jooste, David Kriel, Jan Serfontein, Sebastian de Klerk; Keagan Johannes, Embrose Papier; Gerhard Steenekamp, Johan Grobbelaar, Mornay Smith, Cobus Wiese, JF van Heerden, Marcell Coetzee (captain), Mpilo Gumede, JJ Theron
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Reps: Juann Else, Alu Tshakweni, Francois Klopper, Nicolas Janse van Rensburg, Nama Xaba, Paul de Wet, Stedman Gans, Willie le Roux.
Ospreys: Jack Walsh; Dan Kasende, Phil Cokanasiga, Keiran Williams, Keelan Giles; Dan Edwards, Reuben Morgan-Williams; Garyn Phillips, Dewi Lake (captain), Tom Botha, Rhys Davies, James Fender, Ross Moriarty, Harri Deaves, Morgan Morse
Reps: Ethan Lewis, Steffan Thomas, Rhys Henry, Huw Sutton, James Ratti, Luke Davies, Tom Florence, Harri Houston
